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The Living World
Biology · Class 11NCERT pp. 1–82 sets × 25 questionsFree
Key facts and formulas for The Living World, three worked sample questions, and two full practice sets. Every question has a hint, a reason for every option and a step-by-step solution, with a calculator or animation where one helps. English and Hinglish.
Key facts for this chapter
| Idea | Rule or fact |
|---|
| Described species | About 1.7 to 1.8 million species are described; insects are the largest group |
| Scientific name format | Genus (capital) + species epithet (small); italics in print, each word underlined by hand; author name at end |
| Codes | ICBN for plants, ICZN for animals; tautonym allowed only in zoology |
| Taxonomic hierarchy | Species, genus, family, order, class, phylum, kingdom (ascending) |
| Name endings | Plant families -aceae, animal families -idae, plant orders -ales |
| Taxon vs category | Category = rank (class); taxon = actual group (Mammalia) |
| Four taxonomy processes | Characterisation, identification, classification, nomenclature |
| Taxonomical aids | Herbarium: dried plants; botanical garden: living plants; museum: preserved specimens; zoo: living animals; key: couplets; monograph: one taxon |
| Living features | Growth from inside; metabolism and awareness are defining; reproduction is not |
Three sample questions
Q1. Which of the following is a technical question that biology tries to answer?
- What is the purpose of life?
- What distinguishes a living organism from non-living matter?
- Which natural forces deserve worship?
- Why should humans be placed at the centre of all biological thought?
Hint and solution
Hint: Biology answers questions that can be studied through observation. Which option asks about the nature of living things versus non-living things?
- Technical question = testable by study — A technical question about life can be investigated with observation and experiment.
- Purpose, worship, human-centred views = philosophy — Options A, C and D are about purpose, belief and values, which biology does not test.
- Living vs non-living is biological — Option B asks what distinguishes living from non-living, which is exactly what biology studies.
- Answer: B — So the technical question is what distinguishes a living organism from non-living matter. Option B.
Answer: B. Biology deals with what makes something living rather than non-living. Purpose is left to philosophy.
Q2. Scientists have so far described about how many species?
- 17 to 18 thousand
- 17 to 18 million
- 1.7 to 1.8 billion
- 1.7 to 1.8 million
Hint and solution
Hint: Think of a number in millions, not thousands or billions. It is under two million.
- Described species ≈ 1.7 to 1.8 million — NCERT states that the number of species known and described is between 1.7 and 1.8 million.
- Check the unit: million, not thousand or billion — Thousands would be too few and billions too many for the species we have named.
- Answer: D — So about 1.7 to 1.8 million species are described. Option D.
Answer: D. The described count is about 1.7 to 1.8 million. It is only the known part of biodiversity.
Q3. Biodiversity is best defined as
- the number and types of organisms on earth
- the number of plant species only
- the number of individuals in one population
- the number of species in one forest only
Hint and solution
Hint: Biodiversity covers all organisms, plants and animals, everywhere on earth. Look for the widest definition.
- Biodiversity = number + types of organisms on earth — The term covers every kind of organism, in every habitat of the earth.
- Reject narrow options — Plants only, one population or one forest are all restricted versions.
- Answer: A — So biodiversity is the number and types of organisms on earth. Option A.
Answer: A. Biodiversity is the number and types of organisms on earth, not limited to plants or one place.
How to use this chapter
Read the NCERT pages first, then attempt Set 1 without the hints. Note every wrong answer in a mistake list, read the reason for each option, and retry Set 2 two days later. A topic is solid when you can say why each wrong option is wrong.